Sometimes you just can't catch a break from either side.
The Rebbe's attendance at university actually hampered his message that college campuses were dangerous places for a Jewish kid to be. Many times in private audience parents raised the issue, "but you attended college!" The Rebbe's reply invariably was that this made him the best judge of the harm the college environment causes. We know that this was not due to opposition to learning a skill, as he established vocational schools for learning a trade. The anti-religious and Bible-critical stance of major universities remains a negative influence on Jewish students attending college.
On the other hand, certain elements went out of their way to point out that whatever Lubavitchers had to say about the Rebbe attending college was a deliberate lie. If they said he was in Sorbonne, it was a lie. If they said he wore a yarmulke and a hat, it was a lie. They claim that Chabad promoted this claim to raise the secular world's admiration for the Rebbe. The earliest I actually remember this claim being raised publicly was in the book "Despite All Odds" of the late eighties, not published by Chabad.
The truth is: Who cares?
Let me make it clear that historical veracity is important, and we should know the precise details of the Rebbe's life when possible.
But truthfully, how does this impact the Rebbe's standing in the world? For over forty years the Rebbe was subject to the most intense public scrutiny. First by his students, who would stand honorary guard over his home during the scant hours a week that he spent there, certainly in his office located 20-30 feet away from the study hall of the Yeshivah, and later by the broader public. The Rebbe's conduct was the same at all times.
I could not care less if the Rebbe had spent the years before his Nesius in a secluded shack in Russia, or if he had spent them as a teacher in Yeshivah, or if he had spent them traveling the world fundraising, or if he had served as a public Chabad leader.
What I care about is the 40 years that the Rebbe chose to share with us, with me, at the cost of his health, his sleep, his family life and personal time. He cut short where he could in anything that did not affect his ability to offer himself to the Chasidim. If the Maamorim could not be written by the Rebbe, at least they were said. If Yechidus had to be stopped after 28 years, at least he could stand for hours for a brief moment with every Jew.
I did not see in a single moment I experienced with the Rebbe, in a single Maamar or Sichah I heard or learned of the Rebbe, in a single story of encouragement and demand of the Rebbe any influence of the Sorbonne. What I did see is the influence of the Rebbe on the Sorbonnes of the world, on Judaism in France, on the college students who found their spirituality in the Yeshivos.